On plexus representation of dissimilarities

Correspondence analysis has found widespread application in analysing vegetation gradients. However, it is not clear how it is robust to situations where structures other than a simple gradient exist. The introduction of instrumental variables in canonical correspondence analysis does not avoid these difficulties. In this paper I propose to examine some simple methods based on the notion of the plexus (sensu McIntosh) where graphs or networks are used to display some of the structure of the data so that an informed choice of models is possible. I showthat two different classes of plexus model are available. These classes are distinguished by the use in one case of a global Euclidean model to obtain well-separated pair decomposition (WSPD) of a set of points which implicitly involves all dissimilarities, while in the other a Riemannian view is taken and emphasis is placed locally, i.e., on small dissimilarities. I showan example of each of these classes applied to vegetation data

Original treatment of constitutional painful callosities by surgical excision, collagen/elastin matrix (MatriDerm (R)) and split thickness skin graft secured by negative wound therapy

National audienceConstitutional painful callosities is an unusual pathology, integrated in the frame of "palmoplantar keratodermia" (PPK). Lesions are located at areas of support of the sole. These lesions are painful and disable the normal walking. Treatments are suspensive and painkillers. We report our experience of a single surgical treatment: surgical excision, split thickness skin graft applied on a dermal substitute and secured by negative wound therapy. A 28-year-old patient, affected by this disease, has a desire of pregnancy but her treatment is highly teratogen. A year post-op, wounds were healed. The walk was possible with a relief of the pain, without any ulcerations. The surgical treatment by excision and graft or flaps was previously reported for PPK. The use of dermal substitute was never described for this indication. Dermal substitute compensate the thickness of the soft tissue defect and give an accurate quality of elasticity in this localisation. The negative wound therapy enhances the quality and shortens the length of graft taking, and the adhesion of the dermal substitute on his bed. (C) 2009 Elsevier Masson SAS. All rights reserved